球形催化剂颗粒内气体扩散及其有效因子

Efficiency Factor and Gas Diffusion in Spherical Catalyst Particles

研究了三元催化器处理天然气汽车尾气过程中球形催化剂颗粒内的尾气扩散系数、浓度分布以及催化剂有效因子(η)等影响因素。结果表明,适当增大催化剂颗粒的平均孔半径或增大分子的平均自由程,可使扩散系数在整个催化剂颗粒内均保持较高的值。随Thiele模数(Φ_s)值的减小,催化剂颗粒内的相对浓度分布更为均匀,且呈整体增大的趋势,有效因子也增大。要消除内扩散的影响,使η相对较大,应降低Φ_s的值,并保持在0.0～0.5。

The factors influencing internal diffusion coefficient, concentration distribution and efficiency factor of natural gas vehicle tail gas in spherical catalyst particles in the three-way catalytic converter were investigated. The results showed that increasing average radius of pores or increasing molecule average free journey could keep the internal diffusion coefficient high in the whole spherical catalyst particles. With the decrease of thiele modulus （Фs）, the relative concentration in the whole catalyst particles became more uniform and higher, and the efficiency factor became larger. The internal diffusion could be eliminated and the efficiency factor could be increased by decreasing ~s and keeping it at 0.0-0.5.